Explore the vast range of titles available.

Nanoscale view of cell membrane lipids Cholesterol-mediated lipid interactions, such as nanodomain formation, are considered vital in a cell, but because of the lack of suitable detection techniques, their spatiotemporal range remained highly controversial. Here, Eggeling et al . use subdiffraction-resolution STED (stimulated emission depletion) fluorescence microscopy to detect the diffusion of single lipids or glycosylphosphatidylinositol (GPI)-anchored proteins on the plasma membrane of a living cell. Tuning the probing spot area up to about 70-fold below that of a confocal microscope reveals that unlike phosphoglycerolipids, sphingolipids and GPI-anchored proteins are trapped for about 10 ms in cholesterol-mediated complexes within less than 20 nm space. Optical probing in nanosized areas is a powerful new approach to study biomolecular function. Here, subdiffraction-resolution STED fluorescence microscopy is used to detect the diffusion of single lipids or GPI-anchored proteins on the plasma membrane of a living cell. Tuning the probing spot area ∼70-fold below that of a confocal microscope reveals that unlike phosphoglycerolipids, sphingolipids and GPI-anchored proteins are trapped for ∼10 ms in cholesterol-mediated complexes within <20 nm space. Cholesterol-mediated lipid interactions are thought to have a functional role in many membrane-associated processes such as signalling events 1 , 2 , 3 , 4 , 5 . Although several experiments indicate their existence, lipid nanodomains (‘rafts’) remain controversial owing to the lack of suitable detection techniques in living cells 4 , 6 , 7 , 8 , 9 . The controversy is reflected in their putative size of 5–200 nm, spanning the range between the extent of a protein complex and the resolution limit of optical microscopy. Here we demonstrate the ability of stimulated emission depletion (STED) far-field fluorescence nanoscopy 10 to detect single diffusing (lipid) molecules in nanosized areas in the plasma membrane of living cells. Tuning of the probed area to spot sizes ∼70-fold below the diffraction barrier reveals that unlike phosphoglycerolipids, sphingolipids and glycosylphosphatidylinositol-anchored proteins are transiently (∼10–20 ms) trapped in cholesterol-mediated molecular complexes dwelling within <20-nm diameter areas. The non-invasive optical recording of molecular time traces and fluctuation data in tunable nanoscale domains is a powerful new approach to study the dynamics of biomolecules in living cells.